1st Post, Probably in the wrong place....

[sheeter]

Yikes.... I was hoping to find some basic information here but dang.... I feel like i just stepped into the mega-warehouse in the Indiana Jones movie where they stored the Arc of the Covenant....

I am looking to build my 1st CNC mill.

It is planned to be a "mini-mill"

I have my Stepper Motors
"STP5802017" (4 phase, .8a/phase 1.8deg, unipolar 6 wire)

I am trying to find a BASIC walk-through of the current methodologies for driving/controlling these from MACH3.

Every "Basic's page" that I find goes into the windings, the voltage and current readouts, the torque, etc... Important stuff but for the love of god, can anybody discuss the actual basic basics....

Like, should/could I use;

1. a simple breakout box and then 4 driver boards or....
2. a "controller" like those on ebay (4 Axis Stepper Motor Drive Board TA8435H Controller) or (4 Axis TB6560AHQ Stepper Motor Driver Controller(0.5A-2.5A)) and hook the motors directly..
3. something else

I am trying to do this as inexpensively as I can at first to learn, but I cannot afford to just "buy it and try it"

Thanks for hosting this site (wow) and thanks in advance for any assistance.

Steve

[doorknob]

There might be a better subforum to ask the questions than this one, but I won't hold it against you.

There is no single answer to your questions, though.

A breakout board with separate drivers has some advantages - for example, if something goes wrong with one axis, it may be easier to troubleshoot or repair than it would be if you were using an all-in-one solution.

On the other hand, a combination board that has the breakout functionality built in may be less expensive than using separates.

As far as the specific combination board that you are considering, some people have had success with those while others have had problems. There is a lot of good information (but it's a long read) in the following thread:

http://www.cnczone.com/forums/genera...y_chinese.html

A problem with keeping things inexpensive to start is that you may "grow out of" your first system quickly, so that in the longer run you end up spending more money than if you had gone with a more expensive set-up to start with.

I did not find any info about the stepper motors that you mentioned, but my guess is that they are not very powerful. Do you know what the holding torque rating of those motors is? What kind of mini mill are you contemplating modifying for CNC?

[sheeter]

Thanks for the reply!

I actually read that whole thing.... It convinced me NOT to go the chinese provider route.

I am making the mill myself.

I am using aluminum extrusion for the frame, u channel for the rails, and lexan for the stage.

This is the "build it cheap and use it to make the parts for a better one" plan...

I will be milling within 3"x6x3" range and most within 3"x3"x1" in steel or aluminum.

Cutting time is irrelevant to my needs. Mostly I am making dies for my punch press.


I have attached a PDF of the specs for my steppers.


any thoughts about this product?
http://www.phidgets.com/products.php...roduct_id=1062

Steve

[jalessi]

Sheeter,

If you want a inexpensive solution and have a soldering iron take a look at the HobbyCNC drive.

HobbyCNC EZ Driver Board Kit | HobbyCNC

Your stepper motor torque output is on the feeble end of the spectrum, I would suggest holding off on making any more purchases until you have a more complete game plan.

Jeff...

[doorknob]

I have attached a PDF of the specs for my steppers.


any thoughts about this product?
Phidgets Inc. - Unique and Easy to Use USB Interfaces

I agree that the motor's torque rating is on the low side of what is usually employed for all but the smallest machines.

As for the phidgets driver, I do not have direct experience with it. The board may be OK to pair up with that motor (although the motor's inductance is fairly high for the low voltage that it will be driven with), in that it is designed to drive a set of unipolar motors with a an amp or less of current, but it may not be the best choice for your application.

That board is probably intended for use with small robots. It is intended to be driven by providing step commands from custom software, sent over the USB port. I sincerely doubt that you will be able to drive it with Mach3 or EMC2. I'm not sure that you will be able to drive it from any CAM software output without doing a lot of custom programming (but I have not done any research into whether or not anyone provides such software).

Your plan to mill some steel parts will probably raise a few eyebrows, even if the parts are small and do not require high speed from your machine.

[sheeter]

Thanks again!

I knew that the motors are a bit light but am curious to see what the results will be.

I also made a pneumatic power hammer and was told over and over that I was making it too small/light/weak. The reality is that most folks seem to feel that it is some form of "measuring contest" that the unit need to be as powerful as possible. I made mine to replicate my strength +10%. works like a champ, keeps me from blowing an elbow when making armor.

That Hobby CNC looks great. I may just go that route.

Steve

[sheeter]

Ok,

So to see if I am way off base here.

In your opinion, would this combination be reasonable?

Breakout board:
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

Driver Boards:
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

I am trying to not support direct purchases from China, but the funny thing about Ebay, if you select "north america" only, your options get cut in half and double in price... Sigh....

Thank you for your time and thoughts.

I am reading about this technology as fast as I can but wow...

is there a "Dumb questions" section here? I would like to ask questions like...

What is PIC and/or what does PIC stand for
What are Shields?
Why are controllers not commonly set up as PC boards?
Can a geared/belt driven stepper be used as the spindle?

[doorknob]

I am reading about this technology as fast as I can but wow...

is there a "Dumb questions" section here? I would like to ask questions like...

What is PIC and/or what does PIC stand for
What are Shields?
Why are controllers not commonly set up as PC boards?
Can a geared/belt driven stepper be used as the spindle?

I haven't yet looked at those eBay links, but I have a few comments on your other questions.

What is PIC and/or what does PIC stand for

A PIC is any one of a family of microcontrollers (integrated circuits or ICs) manufactured by the Microchip Technology, Inc. Microchip Technology Inc. is a Leading Provider of Microcontroller and Analog Semiconductors, providing low-risk product development, lower total system cost and faster time to market for thousands of diverse customer applications worldwide.

They are popular because they are inexpensive, easily available, relatively fast and capable microcontrollers. They are used in industry as well as by hobbyists. A number of DIY stepper drivers have been designed and built based on PICs. Since there are several different families of PICs that are available, the above is just a generalization, and it is necessary to examine the characteristics of a specific family of parts and further to examine the capabilities of a specific part number within a family to truly understand the features of any given PIC.


What are Shields?

There is a series of microcontroller-based open source hardware and software designs (and actual hardware) collectively referred to as "Arduino boards" that is popular with electronic and robotic hobbyists. See Arduino - HomePage. Part of the Arduino design is a common electrical and mechanical interface that permits additional boards to be stacked onto and electronically connected to the board that holds the main Arduino microcontoller. Such add-on boards are called "shields". They have many different functions. So, for example, a bare-bones add-on board may be called a "protoshield", while an add-on board that is designed to interface to stepper motors via use of the GRBL programming interface is called a "grblshield". Arduino boards do not use PIC microcontrollers on their main board, rather they generally use microcontrollers made by Atmel.

Why are controllers not commonly set up as PC boards?

I'm not sure that I understand that question. Lots of stepper motor drivers are set up as PC boards.


Can a geared/belt driven stepper be used as the spindle?

I'm not sure that I can give a satisfactory answer to that question, other than to note that stepper motors have their greatest torque at low speeds, whereas various commonly-used materials are best machined at speeds much faster than is generally available through stepper motors, geared or not. Steppers are usually intended for applications that can make good use of relatively precisely known step positions (or fractions thereof) without a complicated control mechanism. That is a very different application than the typical spindle application, which does not normally require precise steps, but rather calls for high power at high speeds with continuous rotation of the tooling.

[doorknob]

Ok,

So to see if I am way off base here.

In your opinion, would this combination be reasonable?

Breakout board:
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

Driver Boards:
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

I am trying to not support direct purchases from China, but the funny thing about Ebay, if you select "north america" only, your options get cut in half and double in price... Sigh....

While I do not have direct experience with that particular breakout board, judging by the specs it looks like it could be a useful and inexpensive board. It does not appear to have all of the flexibility or features of some other boards that I have seen, but the advantage of that is that there is less chance of running into confusion about how to set up jumper options and wire up the board.

The ULN2003 boards are not really what you are looking for and will not drive your stepper motors without designing and adding a lot of circuitry to them. Instead, it looks like the boards are mainly just carriers for the chips with a minimum of support circuitry, and the function of the chips is very limited - namely, to switch the power on and off to electronic components such as motor windings.

To explain further, those boards do not contain any circuitry to permit you to connect up step and direction signals, and then interpret those signals to turn the stepper motor windings on and off in the proper pattern that will rotate the motor shaft correctly.

So, unless you are looking for an electronic design project, you should probably stay away from the ULN2003 boards.

[sheeter]

Doorknob,

Excellent replies(x2)

Much more sense has been made...

Simple is good.

Better driver boards.. got it. I'll keep looking and reading and see if I can come up with a set that I can afford.

I am fairly skilled at PCB work, so I am strongly considering going all the way to making a set of boards from the existing designs. Will let me learn and build (love that part)

I do not want to put anyone on the spot, but with the caveat that I am trying to be under $100 for the boards and bits, are there any recommendations for "try this" or "avoid that"? HobbyCNC or Arduino?

Thanks again, really appreciate the patience with this old Noob who has more brains then sense and never enough money....

Steve

[doorknob]

I don't have direct experience with the HobbyCNC boards either, but they seem to get good marks from users here, and you don't need a separate breakout board with them. The tradeoff for the low price is that you have to put in the time to solder them up.

[jalessi]

I agree, with enough time its possible to carve Mount Rushmore by hand with a hammer and chisel.

I knew that the motors are a bit light but am curious to see what the results will be.

I also made a pneumatic power hammer and was told over and over that I was making it too small/light/weak. The reality is that most folks seem to feel that it is some form of "measuring contest" that the unit need to be as powerful as possible. I made mine to replicate my strength +10%. works like a champ, keeps me from blowing an elbow when making armor.

Steve